Foundations for "International Cooperation in the Field of Hydrography": Some Contributions by British Admiralty Hydrographers, 1795-1855

Great Britain established its Hydrographic Office in 1795 with a remit to produce charts for the use of its Navy. As time progressed and Hydrographers to the Admiralty Board changed so did the remit of the Hydrographic Office. As a facet of the steady development of Office activities there was an underlying theme of international cooperation, which resulted in British Hydrographers entering into correspondence and agreements with their international counterparts. Some of those activities are examined in this paper to hopefully redefine the International Hydrographic Bureau’s statement that ‘International cooperation in the field of hydrography began with a Conference held in Washington in 1899.Gran Bretaña fundó su Servicio Hidrográfico en 1795 con un mandato para producir cartas para su uso por la Marina. El tiempo ha pasado y del mismo modo que los Hidrógrafos del Consejo del Almirantazgo han cambiado, así ha sucedido con el mandato del Servicio Hidrográfico. Como faceta del desarrollo estable de las actividades del Servicio había un tema fundamental de cooperación internacional, cuyo resultado fue que los Hidrógrafos Británicos iniciaron un intercambio de correspondencia y acuerdos con sus homólogos internacionales. En este artículo se examinan algunas de esas actividades, esperando definir de nuevo la declaración del Bureau Hidrográfico Internacional según la cual ‘la cooperación internacional en el campo de la hidrografía empezó con una Conferencia celebrada en Washington en 1899.La Grande-Bretagne a établi son Service hydrographique en 1795 avec pour mission de produire des cartes devant être utilisées par sa Marine. Par la suite, cette mission se modifia à mesure que les hydrographes du Conseil de l’Amirauté se renouvelèrent. L’une des facettes du développement régulier des activités du Service hydrographique fut le thème fondamental de la coopération internationale qui incita les hydrographes britanniques à entrer en correspondance et à passer des accords avec leurs homologues internationaux. Quelques unes de ces activités sont passées en revue dans l’article qui suit, avec pour dessein de redéfinir la déclaration du Bureau hydrographique international d’après laquelle la coopération internationale dans le domaine de l’hydrographie a commencé lors de la conférence tenue à Washington, en 1899

The southern termination of the East Madagascar current

The Agulhas Current system is a vital part of the global thermohaline circulation. This global thermohaline overturning of the oceans has in turn an inextricable link to world climate. Although this current is so important, relatively little is known on its sources. One of these proposed sources of the Agulhas Current is the southern limb of the East Madagascar Current (EMC). Previously the EMC was primarily studied through the use of drifters, remote sensing and ships' drift methods. In an attempt to increase the understanding of this possible source region a first dedicated cruise was organised for the southern termination of the EMC. The cruise took place in March 2001. The hydrographic and other data from the cruise have the potential to describe the EMC termination in a seminal way. The EMC is shown to consist of Tropical Surface Water, Subtropical Surface Water and South Indian Central Water. In the region of the EMC Antarctic Intermediate Water, North Indian Deep Water and North Atlantic Deep Water/Circumpolar Deep Water were found. There is clear evidence of the presence of Red Sea Intermediate Water with salinities greater than 34.5 psu at temperatures between 4 and 6.5°C from 800-1250 m, inshore of the EMC. The width of the current during the cruise period was 100 km, the maximum speed of the current was 1.1 m/s and the depth of the current was 1000 m. The maximum transport of the EMC was calculated to be 39.3 Sv. An EMC undercurrent was found with a depth range of 1000-2000 m. The maximum speed of the undercurrent was seen to be 0.3 mis and the transport of the undercurrent was 0.8 Sv. No retroflection of the EMC emerges from this data set. Satellite geostrophics over a period of 13 years give evidence of eastward flow being associated with eddies in the region of the EMC termination. References have suggested that such eddies may give the appearance of a retroflection. From the observations there was ample evidence for the presence of a relatively weak upwelling cell inshore of the EMC. The temperature at the surface of the upwelling cell was 26°C (2 degrees less than the surrounding water) and the chlorophyll concentration was 0.63 mg Chl-a/m3 . Nitrate concentration was 6.4 µmol/kg at 100 m, phosphate 0.53 µmol/kg, silicate 5.69 µmol/kg and oxygen was 107.5 µmol/kg. At 45 km from the coast there was an average movement of water offshore down to a depth of 40 m. The maximum speed of the offshore flow was 0.5 m/s

Re-evaluation of the role of intramuscular ephedrine as prophylaxis against hypotension associated with spinal anesthesia for Caesarean section

A research report submitted to the Faculty of Medicine, University of Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Medicine in the branch of Anaesthesia.Spinal anaesthesia for Caesarean section is associated with an unacceptably high incidence of hypotension despite the administration of an intravenous fluid preload and the use of uterine displacement. The theoretical benefits of preventing hypotension as opposed to treating it as it occurs are the avoidance of considerable maternal discomfort, a reduced risk of serious cardiovascular or respiratory depression and the avoidance of transient foetal asphyxia. The use of prophylactic intramuscular ephedrine prior to spinal anaesthesia has been recommended but not well studied. The advantages of the intramuscular route for ephedrine administration are its simplicity and its favourable pharmacokinetic profile. Cardiovascular support is sustained throughout the surgery and into the post operative period. Opposition to the use of intramuscular ephedrine in the prevention of hypotension is based on two studies in which spinal anaesthesia was not used [1,2]. These studies showed an unacceptably high incidence of hypertension, a deleterious effect on foetal gas exchange and a lack of efficacy when intramuscular ephedrine was used in epidural and general anaesthesia respectively. This research report describes a randomised, double blind, interventional study designed to assess the safety (prevalence of hypertension, tachycardia or foetal compromise) and efficacy (prevalence of hypotension) of 37,5mg of ephedrine given prior to spinal anaesthesia for Caesarean section. Forty patients who had given informed consent were entered into the study. Blood pressures and pulse rates were recorded for 90 minutes after ephedrine administration, samples of umbilical venous blood were collected and Apgar scores assessed. This study found that giving 37,5mg of intramuscular ephedrine prior to spinal anaesthesia was safe from a maternal point of view in that it was not associated with reactive hypertension or tachycardia. When the ephedrine was given 10 minutes prior to induction of the spinal the technique proved to be effective in reducing the incidence and severity of hypotension. When used in the above manner the technique was not associated with foetal depression or acidosis.WHSLYP201

The Expansion of British Naval Hydrographic Administration, 1808-1829

The period from 1808 to 1829, largely neglected by those historians who have looked at the Hydrographic Office, was the crucial formative period for expansion that laid the solid foundations which later Hydrographers could then exploit. The context, achievements and failures of the Admiralty’s hydrographic function, including surveying, chart production, supply, sales and its contribution to the Navy and the scientific world, as an all encompassing beast has been overlooked; the Admiralty placed the responsibility for those tasks on the shoulders of its Hydrographer. Subsequently he determined the success or failure of the office, using his initiative to expand and develop opportunities benefiting the Admiralty, as well as managing a valuable resource of geographical intelligence, fostering links with scientists and the international hydrographic community. The Hydrographer also found himself creating his own policies, serving as Secretary to the Board of Longitude, being a consultant on navigational matters, taking responsibility for the acquisition, supply and maintenance of chronometers for the Navy, as well as being a focal point for issues concerning pay, promotion and manning for surveying specialists. The period from 1808 to 1829 saw many changes, which gave rise to numerous opportunities for expansion. The Admiralty Board and William, Duke of Clarence (as the last Lord High Admiral), both had a direct influence in the way the office expanded, which saw innovation and experimental work become part of the Hydrographer’s routine, especially after the Peace of 1815. But expansion required funding and at a time when internal economy appeared to the be the main objective within the Admiralty, Captain Thomas Hurd managed not only to establish a 100% increase in surveying capacity but laid the foundation for a distinct specialist and professional core of survey officers. His successor, Captain William Parry, despite his absences, overhauled working practices in the office, set standards for surveyors to follow and continued to expand the number of survey ships in commission. Subsequently Captain Francis Beaufort was left the most highly efficient hydrographic office since its foundation in 1795

MEMS 411: Just Putt It in Drive

The ASME Student Design Challenge 2023: mini golf challenge

A critique of the hypothesis that CA repeats are primary targets of neuronal MeCP2

The DNA-binding protein MeCP2 is reported to bind methylated cytosine in CG and CA motifs in genomic DNA, but it was recently proposed that arrays of tandemly repeated CA containing either methylated or hydroxymethylated cytosine are the primary targets for MeCP2 binding and function. Here we investigated the predictions of this hypothesis using a range of published datasets. We failed to detect enrichment of cytosine modification at genomic CA repeat arrays in mouse brain regions and found no evidence for preferential MeCP2 binding at CA repeats. Moreover, we did not observe a correlation between the CA repeat density near genes and their degree of transcriptional deregulation when MeCP2 was absent. Our results do not provide support for the hypothesis that CA repeats are key mediators of MeCP2 function. Instead, we found that CA repeats are subject to CAC methylation to a degree that is typical of the surrounding genome and contribute modestly to MeCP2-mediated modulation of gene expression in accordance with their content of this canonical target motif

Scale‐invariance of albedo‐based wind friction velocity

Obtaining reliable estimates of aerodynamic roughness is necessary to interpret and accurately predict aeolian sediment transport dynamics. However, inherent uncertainties in field measurements and models of surface aerodynamic properties continue to undermine aeolian research, monitoring, and dust modeling. A new relation between aerodynamic shelter and land surface shadow has been established at the wind tunnel scale, enabling the potential for estimates of wind erosion and dust emission to be obtained across scales from albedo data. Here, we compare estimates of wind friction velocity (u * ) derived from traditional methods (wind speed profiles) with those derived from the albedo model at two separate scales using bare soil patch (via net radiometers) and landscape (via MODIS 500 m) datasets. Results show that profile‐derived estimates of u * are highly variable in anisotropic surface roughness due to changes in wind direction and fetch. Wind speed profiles poorly estimate soil surface (bed) wind friction velocities necessary for aeolian sediment transport research and modeling. Albedo‐based estimates of u * at both scales have small variability because the estimate is integrated over a defined, fixed area and resolves the partition of wind momentum between roughness elements and the soil surface. We demonstrate that the wind tunnel‐based calibration of albedo for predicting wind friction velocities at the soil surface (u s* ) is applicable across scales. The albedo‐based approach enables consistent and reliable drag partition correction across scales for model and field estimates of u s* necessary for wind erosion and dust emission modeling